It is desirable, for vehicle strengthening members, to maximize impact energy absorption and bending resistance while minimizing mass per unit length of the strengthening member. Impact energy absorption may be maximized, for example, by assuring that the strengthening member compacts substantially along a longitudinal axis of the strengthening member upon experiencing an impact along this axis. Such longitudinal compaction may be referred to as a stable axial crush of the strengthening member.
When a compressive force is exerted on a strengthening member, for example a force due to a front impact load on a vehicle's front rail or other strengthening member in the engine compartment, the strengthening member can crush in a longitudinal direction to absorb the energy of the collision. In addition, when a bending force is exerted on a strengthening member, for example a force due to a side impact load on a vehicle's front side sill, B-pillar or other strengthening member, the strengthening member can bend to absorb the energy of the collision.
Conventional strengthening members rely on increasing the thickness and hardness of corner portions to improve crush strength. However, such increased thickness and hardness increases weight and decreases manufacturing feasibility. It may be desirable to provide a strengthening assembly configured to achieve the same or similar strength increase as provided by the thickened corners, while minimizing mass per unit length of the member, and maintaining a high manufacturing feasibility.
It also may be desirable to provide a strengthening member that can achieve increased energy absorption and a more stable axial collapse when forces such as front and side impact forces are exerted on the strengthening member. Additionally, it may be desirable to provide a strengthening member that possesses improved noise-vibration-harshness performance due to work hardening on its corners.
It also may be desirable to provide structures to connect the strengthening member to another automotive component to promote a stable axial crush. When the other automotive component has a different shape than the strengthening member, it may be difficult to apply welding techniques to connect the strengthening member and the other component due to the variation in shape. This difficulty may result in a connection that is not secure and which causes an unstable axial crush.